Why Is Facebook CEO Mark Zuckerberg Smiling? Maybe because someone might be willing to pay $100 to send him a message.

Paul Sakuma/AP

If you're a casual observer of the stock market, the last time you tuned in to what was happening with Facebook's stock was probably last May.

In those days after the company's long-anticipated initial public offering, its price was diving daily — exactly the opposite of what many had expected given the hype leading up to Facebook's IPO.

The IPO itself was full of technical problems — many buyers weren't sure if their orders went through. And then there were questions about whether Facebook could figure out how to make money in its fastest-growing segment — mobile.

What a difference several months make. Since the start of 2013, Facebook's stock has jumped 19 percent, closing at $31.72 on Friday. It's up nearly 81 percent since its rock-bottom low of $17.55 on Sept. 4.

"The trend is clear from the start of the year, with few days of declines in between; investors have found new love for the social giant," says The Next Web. It didn't hurt that a Merrill Lynch report predicted that in 2014 Facebook's mobile revenue will top the money it makes from its desktop users.

There's also speculation that Facebook will have something big to say at a press event next Tuesday. The company teased reporters with an invitation to "come and see what we're building."

Bloomberg said Facebook could use the event "to assuage user concerns about ad policy changes for its Instagram photo-sharing service." Seeking Alpha has rounded up rumors about the event, which include the recurring idea that Facebook will launch its own smartphone.

Seeking Alpha contributor Timothy Phillips thinks Facebook is likely to tout an e-commerce strategy. It has "already quietly entered the e-commerce business through its proprietary gift service (through the acquisition of Karma), which I think can be a real game changing concept for how consumers purchase," he wrote.

Facebook is looking at all kinds of ways to make money off its 1 billion users. For instance, the company could charge users to send messages to popular people on Facebook. Mashable discovered a test in which users could send CEO Mark Zuckerberg a message — "for a cool $100."

"Keen Facebook observers will recognize this as a variant on the $1 pay-to-message plan that the social network has been experimenting with for months. The company indicated at the time that it would be experimenting with other prices, so it's possible we're starting to see the fruits of that."

The Wall Street Journal's Digits blog points out that Facebook sees this as a way to reduce incoming spam for high-profile Facebook users: "For a normal user, $1 might seem like a lot to send a message to a friend, but for a fan to ensure that someone like Justin Bieber receives a message, it might not be that much."